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Smoothening the Motion-field & Optical-flow of Video

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Hayden Martin
Smoothening the Motion-field & Optical-flow of Video
on Jul 10, 2015 at 6:52:39 am


I've shot footage of models against green-screen on a 2.5K camera at 25p knowing that I cannot shoot any faster to achieve slow motion - to give me a higher degree of flexibility when it comes to remapping their movement I coordinated the models to move as slowly as possible.

Playing back the motion at 100% looks relatively smooth, although giveaways are apparent in the motion - whilst slowly changing poses from A to B, the models struggled to do so with absolute fluidity as observed in real slow motion where the movement would typically be fast whilst shot on a higher frame-rate...

My question is this:

If I want to eliminate minor bumps in the fluidity of the motion from pose A to B, could I simply run an analyses of the footage's Motion-field / Optical-flow then create a smoothen effect that essentially averages out this data in iterations of 100 frames...?

It seems feasible, and theoretically easier if shot against green-screen as there would be no interfering FG / BG information...

I've asked a similar question before but was redirected to interpolation hardware - I am sure my aims could be achieved through good use of expressions though...

Many thanks,

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Walter Soyka
Re: Smoothening the Motion-field & Optical-flow of Video
on Jul 10, 2015 at 3:59:43 pm

If you want to try processing the motion vectors, you'll need a tool that gives you access to them. Twixtor Pro allows you to import/export motion vectors. Maybe you could try the demo to see if you can get the effect you're looking for?

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive [twitter]   |   RenderBreak [blog]   |   Profile [LinkedIn]

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Chris Wright
Re: Smoothening the Motion-field & Optical-flow of Video
on Jul 10, 2015 at 5:03:12 pm
Last Edited By Chris Wright on Jul 10, 2015 at 5:04:18 pm

AE's timewarp can set vectors numbers higher, it supports roto masks if you precomp, so the bg won't get interpolated.
Also, you can precomp a video, precompose it, right click timestretch 50%, then apply timewarp 50% to the precomp.
That will create,decimate and average movement long as both numbers match. The higher the number, the more interpolation at a cost of softness.

filter-extreme will reduce softening of the image, but at a huge cpu cost.

If you need perfect quality, terrenex came out with a mini-hardware box. Or as walter said, twixtor pro has spline support to manually guide the warping.

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